perf/x86/intel/uncore: Fix missing marker for snr_uncore_imc_freerunning_events

An Oops during the boot is found on some SNR machines.  It turns out
this is because the snr_uncore_imc_freerunning_events[] array was
missing an end-marker.

Fixes: ee49532b ("perf/x86/intel/uncore: Add IMC uncore support for Snow Ridge")
Reported-by: Like Xu <like.xu@linux.intel.com>
Signed-off-by: Kan Liang <kan.liang@linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Tested-by: Like Xu <like.xu@linux.intel.com>
Cc: stable@vger.kernel.org
Link: https://lkml.kernel.org/r/20200116200210.18937-1-kan.liang@linux.intel.com

arch/x86/events/intel/uncore_snbep.c

@@ -4536,6 +4536,7 @@ static struct uncore_event_desc snr_uncore_imc_freerunning_events[] = {
 	INTEL_UNCORE_EVENT_DESC(write,		"event=0xff,umask=0x21"),
 	INTEL_UNCORE_EVENT_DESC(write.scale,	"3.814697266e-6"),
 	INTEL_UNCORE_EVENT_DESC(write.unit,	"MiB"),
+	{ /* end: all zeroes */ },
 };
 
 static struct intel_uncore_ops snr_uncore_imc_freerunning_ops = {